Various reinforcement fibers and their use in a wide variety of applications are known in the art. For example, it is known to add reinforcement fibers to building materials, such as concrete, including asphalt cement concrete and portland cement concrete and the like, to add strength, toughness, and durability, and to improve the integrity of the cement properties. For example, it is known in the art to add reinforcement fibers to concrete to reduce or prevent cracks. Typical reinforcement fibers that are added to concrete include, for example, asbestos fibers, glass fibers, steel fibers, mineral fibers, natural fibers, synthetic fibers (such as polymer and aramid fibers), and cellulose fibers. Some reinforcement fibers are better suited for particular applications than others. For example, asbestos fibers are known to provide effective reinforcement but, due to environmental and health concerns these fibers, are not extensively used. In addition, some fibers are relatively expensive.
Reinforcement fibers are also generally known for use in the drilling industry. Oil, gas and other subterranean wells are made by drilling a borehole into the ground. As the rotating drill works its way through the geological formations, the drill becomes hot and debris from the cuttings, such as rock, dirt and clay, accumulates and fills the hole. A liquid, such as fresh water, salt water or a water and oil mixture, is circulated downwardly through a drill pipe and drill bit and then upwardly through the annulus created between the drill pipe and the wall of the borehole to carry debris out of the borehole, and simultaneously to cool and lubricate the drill. However, the liquid alone typically does not remove enough debris. To improve the levels of debris removal, additives are injected within the liquid through the drill pipe into the well bore. Reinforcement fibers are known in the art for use as an additive to drilling liquids to increase the levels of debris removal. The addition of reinforcement fibers to drilling liquids increases the carrying capacity without increasing the viscosity of the liquid.
In addition to debris removal, reinforcement fibers are added to drilling liquids as a lost circulation material to prevent fluid loss through fissures and pores in the geological formations. Lost circulation generally refers to the undesirable loss of at least a portion of drilling fluid into the subterranean formation penetrated by the well bore, for example, through porous rock or open channels in the formations. Additives in the drilling liquid can function to stem the loss of circulation fluid by sealing the permeability and channel openings of the formations.
Furthermore, it is known to incorporate reinforcement fibers as a lost circulation material into the cement which is used in drilling wells. In drilling a well, a pipe string (e.g., casing and/or liner) may be run into a well bore and cemented in place. A cement composition is pumped into an annulus between the walls of the wellbore and the exterior surface of the pipe string disposed therein. The cement composition sets in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement that supports and positions the pipe string in the wellbore and bonds the exterior source of the pipe string to the subterranean formation. The annular sheath of set cement surrounding the pipe string functions to prevent the migration of fluids in the annulus. The presence of reinforcement fibers in the cement can reduce or preclude voids or cracks in the cement and therefore, reduce or preclude the flow of liquids therethrough.